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Homework Help: Units of solid angle

  1. Apr 28, 2008 #1

    manjuvenamma

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    1. The problem statement, all variables and given/known data
    What are the units of solid angle in other systems ( In SI, it is steradian)


    2. Relevant equations



    3. The attempt at a solution
     
    manjuvenamma, Apr 28, 2008
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  3. Apr 28, 2008 #2

    Hootenanny

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    The solid angle is technically dimensionless, i.e. it has no real units. It is simply 'assigned' the SI unit of 'steradian' to distinguish it from other dimensionless quantities, such as constants etc.

    Therefore, the solid angle has no alternative units other than SI.
     
    Hootenanny, Apr 28, 2008
  4. Apr 28, 2008 #3

    HallsofIvy

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    The first thing I did was use good old "Google" which sent me to Wikipedia:
    http://en.wikipedia.org/wiki/Solid_angle
    where I learned that the corresponding units are "square degree" and "fractional area" (what fraction of a circle does it subtend?).

    I agree with Hootenanny that a solid angle (like any angle) is dimensionless but it appears there are other "assigned" units.
     
    HallsofIvy, Apr 28, 2008
  5. Apr 28, 2008 #4

    Hootenanny

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    I wasn't aware that there were other 'assigned' units for the Solid Angle, I guess I should google more often! Thanks Halls!
     
    Hootenanny, Apr 28, 2008
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